package demo1;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User:咭咭熊
 * Date:2021 - 08 - 04
 * Time:10:25
 */
class ListNode{
    int val;
    ListNode next;

    ListNode() {}

    ListNode(int val){
        this.val = val;
    }
    ListNode(int val,ListNode next){
        this.val= val;
        this.next = next;
    }
}
public class Test2 {

    /***
     * 合并两个有序链表
     * @param l1
     * @param l2
     * @return
     */
    public ListNode mergeTwoLists(ListNode l1, ListNode l2) {

        if(l1 == null){
            return l2;
        }
        if(l2 == null){
            return l1;
        }
        ListNode head = new ListNode(0);
        ListNode cur = head;
        while(l1 != null && l2 != null){
            if(l1.val < l2.val){
                cur.next = l1;
                cur = cur.next;
                l1 = l1.next;
            }else{
                cur.next = l2;
                cur = cur.next;
                l2 = l2.next;
            }
        }
        //当链表l1为空的时候
        if(l1 == null){
            cur.next = l2;
        }
        //当链表l2为空的时候
        if(l2 == null){
            cur.next = l1;
        }
        return head.next;
    }
}
